In the reporting period we have completed a study demonstrating the influence of surface immobilization strategy, as well as the choice of sensor surface, on the resulting distribution of binding affinity and kinetic rate constants for a soluble binding partner. Using a monoclonal antibody against &#946;2-microglublin as a model system, we studied binding to surfaces with different length of carboxymethyl dextran as a polymeric immobilization matrix, functionalized to different densities, and applying either random amine coupling or streptavidin capture. We found surface with short polymer coating to provide the most uniform distribution of sites that are best accessible for the analyte diffusion. This study also demonstrated the utility of our previously developed affinity distribution method in the optimization of sensor surfaces.